Lifeproof can be hit and miss with hearing on either side of a conversation. My son has a Lifeproof case and has faced this same issue. Sometimes all is okay and on other occasions he can not hear the caller or the caller can not hear him. I am currently reviewing a new Lifeproof case for them. So far so good. They have gotten better over the years. Another thing you could do is return it and ask for another in its place.